The present invention relates generally to techniques that respond to light, such as techniques that respond to light based on one or more positions at which the light is provided. Such techniques can, for example, perform photon energy monitoring.
U.S. Pat. No. 6,763,046 describes laser wavelength monitoring using a multiple reflectivity band reflector (MRBR). One or more monitoring photodiodes detect some cavity light passing through a high reflectivity (HR) mirror of a tunable edge-emitting laser. The MRBR can, in an embodiment, be a coating on a light-receiving surface of one of the photodiodes, which receives light filtered by the MRBR. In other embodiments, the MRBR can be in the path of light from the laser to the photodiode. Each photodiode is monitored by a corresponding circuit, and the circuits detect change in electrical characteristics of the photodiodes, such as change in current in response to the amount of light received, and report the change to a processor.
Various other techniques have been proposed for monitoring light from a laser or other light source, including various techniques for monitoring wavelength.
It would be advantageous to have improved techniques for responding to light, including improved monitoring techniques.